1. Field of the Invention
The present invention relates, in general, to pneumococcal fimbrial protein A (PfpA). In particular, the present invention relates to a DNA segment encoding a pneumococcal fimbrial protein A gene (pfpA); polypeptides encoded by the DNA segment; recombinant DNA molecules containing the DNA segment; cells containing the recombinant DNA molecule; a method of producing a pneumococcal fimbrial protein A polypeptide; antibodies specific to pneumococcal fimbrial protein A; and a method of measuring the amount of pneumococcal fimbrial protein A in a sample.
2. Background Information
Disease caused by Streptococcus pneumoniae (pneumococcus) is an important cause of morbidity and mortality in the United States and developing countries (Sorensen, J. et al. (1986) Scand. J. Infect. Dis. 18:329-335; Wall, R. A. et al. (1986) The Gambia. Bull. WHO 64-4:553-558; Walsh, J. A., and K. S. Warren (1979) N. Eng. J. Med. 301:967-974; Williams, W. W. et al. (1988) Ann. Intern. Med. 108:616-625; Yolken, R. H. et al. (1984) J. Clin. Microbiol. 20:802-805). Pneumococcal disease is very prevalent among the very young, the elderly, and immunocompromised persons. Despite its prevalence, diagnosis of the disease continues to be a problem.
Several tests have been developed to detect pneumococcus antigens and/or antibodies as a means of diagnosing pneumococcus infections (Coonrod, J. D., and M. W. Rytel (1973) J. Lab Clin. Med. 81:778-786; Holmberg, H. et al. (1985) J. Clin. Microbiol. 22:111-115; Ingram, D. L. et al. (1983) J. Clin. Microbiol. 18:1119-1121; Jalonen, E. et al. (1989) J. Infect. 19:127-134; Kanclerski, K. et al. (1988) J. Clin. Microbiol. 26-1:96-100; Makela, P. H. (1982) Scand. J. Infect. Dis. Suppl. 36:111-113; Perlino, C. A. (1984) J. Infect. Dis. 150:139-144; Sippel, J. E. et al. (1984) J. Clin. Microbiol. 20:884-886; Whitby, M. et al. (1985) J. Clin. Pathol. 38:341-344; Yolken, R. H. et al. (1984) J. Clin. Microbiol. 20:802-805). The sensitivity of existing antigen detection tests utilizing body fluids such as serum and urine, remains very low (Ajello, G. W. et al. (1987) J. Clin. Microbiol. 25:1388-1391; Anhalt, J. P., and P. K. W. Yu (1975) J. Clin. Microbiol. 2:510-515; Bartram, C. E. Jr. et al. (1974) J. Lab. Clin. Med. 83:591-598; congeni, B. L. et al. (1984) Ped. Infect. Dis. 3:417-419; Coonrod, J. D. (1983) Proceedings of the American Journal of Medicine Symposium, Jul. 28, 1983, Am. J. Med. 75:85-92; Coovadia, Y. B. and K. K. Naidu (1985) J. Clin. Pathol. 38:561-564; Dilworth, J. A. (1975) J. Clin. Microbiol. 2:453-455; Doskeland, S. O., and B. P. Berdal (1980) J. Clin. Microbial. 11:380-384; Martin, S. J. et al. (1987) J. Clin. Microbiol. 25:248-250), except for antigen detection in cerebrospinal fluids (Henrichsen, J. et al. (1980) J. Clin. Microbiol. 11:589-592; Ingram, D. L. et al. (1983) J. Clin. Microbiol. 18:1119-1121; Lenthe-Eboa, S. et al. (1987) Eur. J. Clin. Microbiol. 6:28-34; Tilton, R. C. et al. (1984) J. Clin. Microbiol. 20:231-234; Yolken, R. H. et al. (1984) J. Clin. Microbiol. 20:802-805). The measurement of antibody response to pneumolysin by enzyme immunoassay (ELISA) appears to be promising for presumptive etiologic diagnosis (Jalonen, E. et al. (1989) J. Infect. 19:127-134; Kalin, M. et al. (1987) J. Clin. Microbiol. 25:226-229; Kanclerski, K. et al. (1988) J. Clin. Microbiol. 26-1:96-100), but the sensitivity and specificity of the test need improvement.
Although a positive blood culture is diagnostic for pneumococcus disease, most patients with bacterial pneumonia do not have bacteremia (Austrian, R. (1974) Prev. Med. 3:443-445; Austrian, R., and I. Gold (1964) Ann. Intern. Med. 60:759-776; Kalin, M. and A. A. Lindberg (1983) Scand. J. Infect. Dis. 15:247-255). The value of sputum cultures has also been questioned because of contamination of the specimens with pharyngeal flora that can include pneumococci (Barrett-Cooner, E. (1971) Ann. Rev. Resp. Dis. 103:845-848). Thus, clinical laboratories are rarely successful in establishing a firm bacterial etiology for those patients with respiratory infections diagnosed presumptively as pneumococcus pneumonia. Researchers have been in constant search for immunodiagnostic markers or tests to aid in the early diagnosis of pneumococcus infections.